Gerhard F. Weinbauer

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BACKGROUND An intense debate is ongoing regarding options for fertility protection in oncological patients. Germ cell transplantation has been applied to restore mouse spermatogenesis. Here, an attempt to apply autologous germ cell transplantation to a primate animal model is described. METHODS Five adult male cynomolgus monkeys were biopsied to retrieve(More)
Spermatogenesis is a complex developmental process that occurs in several phases. A large number of genes have been identified that are expressed during spermatogenesis, but the biological significance of many of these is not yet known. We have used gene targeting to selectively eliminate the transcription factor CREM (cyclic AMP- responsive element(More)
Mice lacking the functional cAMP responsive element modulator (CREM) gene, a component of cAMP-mediated signal transduction, exhibit a specific arrest of round spermatid development although follicle stimulating hormone (FSH) and androgen secretion are not impaired. We studied testicular expression of CREM protein by immunocytochemistry in four patients(More)
This study examined the effect of GnRH-antagonist (GnRH-A)-induced gonadotrophin withdrawal on numbers of germ cells in adult cynomolgus monkeys and aimed to identify the site of the earliest spermatogenic lesion(s) produced. Animals received either GnRH-A (Cetrorelix; 450 micrograms kg-1 day-1 s.c.; n = 5) or vehicle (control, n = 4) for 25 days. One(More)
Germ cell transplantation is a potentially valuable technique offering oncological patients gonadal protection by reinitiating spermatogenesis from stem cells which were reinfused into the seminiferous tubules. In order to achieve an intratubular germ cell transfer, intratubular microinjection, efferent duct injections and rete testis injections were(More)
In comparison with other mammals, human spermatogenesis is known to be an inefficient process, of which germ cell degeneration is a normal part. This study was performed to determine the mechanism of cell death in the testes of elderly men. Testes from 20 patients undergoing orchidectomy for prostate cancer were fixed, sectioned and processed for the(More)
Spermatogenesis is a precisely controlled and timed process comprising mitotic divisions of spermatogonia, meiotic divisions of spermatocytes, and the maturation and differentiation of haploid spermatids. Cell proliferation is controlled by genes involved in the regulation of the cell cycle. Among the principal regulatory proteins are cyclins, which are(More)
By exposing male Djungarian hamsters to short-day photoperiods, a hypogonadotropic condition resembling that of hypophysectomized animals can be achieved without resorting to surgery. By use of this animal model, differential effects of gonadotropins on spermatogenesis have been studied revealing that FSH selectively restimulates spermatogenesis up to the(More)
The possible role of apoptosis in spontaneous or induced germ cell death was investigated by treating adult male rats with either a GnRH antagonist (112.5 micrograms kg-1 day-1 for 14 days) or methoxyacetic acid (650 micrograms kg-1; single dose) or sham-treated with either of the vehicles (n = 3 per group). The antagonist virtually abolished gonadotrophin(More)
The common marmoset, Callithrix jacchus, is the smallest nonhuman primate commonly used in biomedical research. Marmoset characteristics and propensities have enabled them to be used in a wide range of research as a model of human disease, physiology, drug metabolism, general toxicology, and reproductive biology. This paper provides a general overview of(More)